Major
Amiodarone × tacrolimus
Class III antiarrhythmics (Vaughan Williams)×Calcineurin inhibitor (immunosuppressant)
Mechanism
Amiodarone blocks CYP3A4 and P-glycoprotein – two key tacrolimus clearance routes. Tacrolimus plasma levels rise 2- to 3-fold. Additional risk of additive QT prolongation.
Symptoms
Acute nephrotoxicity: rising creatinine and falling glomerular filtration rate. Tremor, headache, hypertension, hyperglycaemia, hyperkalaemia. In transplant patients: accelerated graft function decline.
Management
When combined, reduce tacrolimus by 30–50%; check trough (C0) at days 3 and 7. ECG before start and at 2 weeks; maintain potassium and magnesium. Alternative antiarrhythmic in transplant patients: a beta-blocker for rate control or catheter ablation.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.